Among conventional angular velocity sensors, there is the one which is described, for example, in Patent Document 1. FIG. 5 is a block diagram, showing the configuration of the conventional angular velocity sensor described in Patent Document 1.
An angular velocity sensor 101 shown in FIG. 5 includes an angular-velocity detecting element 102, a drive circuit 103, a detection circuit 104, an output terminal 107, a decision unit 108, and a monitor signal terminal 109. The detection circuit 104 is provided with a first signal processing section 105 and a second signal processing section 106.
The drive circuit 103 drives the angular-velocity detecting element 102. The first signal processing section 105 and the second signal processing section 106 process a signal obtained from the angular-velocity detecting element 102 which moves according to an applied angular velocity. The second signal processing section 106 outputs an angular-velocity signal obtained by this processing to the output terminal 107. The decision unit 108 monitors a signal at a connection point N1 of the first signal processing section 105 and the second signal processing section 106. Then, it decides whether the signal of the connection point N1 is abnormal or not, and outputs a signal which indicates the decision result to the monitor signal terminal 109.
However, in the above described conventional angular velocity sensor 101, a signal is monitored only at the connection point N1 of the first signal processing section 105 and the second signal processing section 106. Hence, a decision cannot be made whether or not a signal is abnormal at a large number of points inside of the angular velocity sensor 101.
Furthermore, in order to monitor an abnormality in the signal of each point in the angular velocity sensor 101 while simultaneously specifying where it is located, monitor signal terminals are required which correspond to the number of numerous points. If a great number of monitor signal terminals are provided, an angular velocity sensor becomes larger. This makes it difficult to miniaturize an angular velocity sensor for integration.
Patent Document 1: Japanese Patent Laid-Open No. 8-327363 Specification